When using new counters with Delta (HP53132A) or Omega (Pendelums Least-Square) estimators for refined frequency resolution, they work by doing a filtered weighing which has a lower bandwidth than the brute force counter, and this will give a lower reading for white and flicker phase noise (see their formulas), and this causes the deception that the ADEV

Hi The TRAIM error will happen with a small number of sats and a location estimate that is less than perfect. I would not go to crazy about that part. First question — why so few sats? You really need to have full screen of locked sats. That can be a feed line / antenna issue. The old Oncore boards are pretty deaf.

Since many counters gate for one second (or gate faster, then average), the ADEV at tau=1 second is a reasonable estimate of the real-world performance of a good counter driven by a GPSDO. Note that, since the ADEV at 1 second depends largely on the OCXO, the heroic tuning efforts mentioned above won't change the ADEV at tau=1 second hardly at all.

So a frequency and temperature time series goes in -- and best fit linear drift and temperature coefficient estimates comes out. This will be automated, but for now I like the plots because they are more educational. Also the eye is extremely good at spotting interesting or unforeseen things that math and statistics are blind to. /tvb

> http://users.megapathdsl.net/~hmurray/time-nuts/leap/UT1-SF-leap.png That's the consequence of Judah Levines approach to interpolate between the projected UT1 offsets, which is estimated per day. > > Somebody asked about systems that "freeze" the clock for a second. Linux, > NetBSD, and FreeBSD all stepped the clock back.

That translates to more noise on the estimates and worse timing ( as well as an impact on location).

For my own part, I will to a poster presentation on  “Reduction of biases in estimated noise power due to sine spurs and narrowband peaks" and a lecture presentation on “Error budget of large time-transfer networks - Theory andpractice from a decade in the field".

Lacking that measurement I use the CPU load and a simple thermal resistance model to estimate the environmental and crystal temperature.

back in the day, with an all analog transponder, you could test at constant frequencies, and do some analytical stuff to estimate incremental ADEV in the turnaround, as well as the imperfections from tracking a higher order variation in Doppler than the loop order. And mission design didn't do orbits around moons, but flybys (e.g.

On Wed, 27 Nov 2019 00:29:19 +0100 Jan-Derk Bakker wrote: > This has yielded a combined "simple" signal > processing path of a differentiator, a double comb filter and the offset > estimator, which is getting very close in performance to the "ideal" band > pass filter (OADEV of 3.77e-13@tau=1s versus 3.25e-13@tau=1s for the BPF; > full plot